On the one hand, I am a strong proponent of free and open-source software and I have contributed to several projects related to porting Linux to embedded hardware, especially mobile phones (htc-linux.org, Replicant and I also consulted some of the FreeSmartPhone.org people). Here are the reasons I like free software (as well as free hardware and free knowledge):
- The most important for me is that you can learn a lot. I have mostly learnt C and subsequently other languages by hacking on the linux kernel and following interesting projects done by fellow developers
- Practically speaking, it is just easier to maintain and develop software when you have the source code
- When you want to share a piece of data or an app with someone, if you deal with closed software, you force them into buying a paid app which may compromise their security
- You can freely distribute your contributions, your cool hacks and research results without being afraid of pursuit by some patent troll
- "Oh, it may threaten your privacy, how can you run untrusted code"? My opinion here is that running untrusted firmwares or drivers for devices is not a big deal because unless you manufacture the SoC and all the peripherals yourself, you can not be sure of what code is running in your system. For example, most X86 CPUs have SMM mode with a proprietary hypervisor, most ARMs have TrustZone mode. If your peripheral does not require you to load the firmware, it just means that the firmware is stored in some non-volatile memory chip in hardware, and you don't have the chance to disable the device by providing it with a null or fake binary. On the other hand, if your device uses some bus like I2C or USB which does not have DMA capabilities or uses IOMMU to restrict DMA access, you are relatively safe even if it runs malicious code.
- "You can examine open source software and find backdoors in it". Unfortunately this is a huge fallacy. First of all, some minor errors which can lead to huge vulnerabilities can go unnoticed for years. Recent discoveries in OpenSSL and GnuTLS came as a surprise to many of us. And then again, have you ever tried to develop a piece of legacy code with dozens of nested ifdefs when you have no clue which of them get enabled in the final build? In this case, analyzing disassembled binaries may even be easier.
- "By developing or using non-free software you support it". In the long run it would be better for humanity to have all knowledge to be freely accessible. However, if we consider a single person, their priorities may differ. For example, until basic needs (which are food, housing, safety) are satisfied, one may resort to developing close-sourced software for money. I don't think it's bad. For me, the motivation is knowledge. In the end, even if you develop stuff under an NDA, you understand how it works and can find a way to implement a free analog. This is actually the same reason I think using proprietary software is not bad in itself. For example, how could you expect someone to write a good piece of free software - an OpenGL driver, an OS kernel, a CAD until they get deeply familiar with existing solutions and their limitations?
In the end, it boils down to individual people and communities. Even proprietary platforms like Palm, Windows Mobile or Apple iOS had huge communities of helpful people who were ready to develop software, reverse-engineer hardware and of course help novices. And there are quite some douchebags around free software. Ultimately, just find the people you feel comfortable around, it is all about trust.